This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In this application, we propose the use of spatially-modulated NIR light (SMNL) to produce quantitative imaging of [unreadable][unreadable]A, [unreadable][unreadable]S', and QY in essentially real-time. The Modulated Imaging group at the Beckman Laser Institute of the University of California, Irvine, has pioneered the use of this technology for quantitative, depth-resolved spectroscopic imaging as part of the NIH Biomedical Technology Center, the Laser Microbeam and Medical Program (LAMMP) at the Beckman Laser Institute (www.bli.uci.edu/lammp). Recent results shown in Preliminary Studies suggest that SMNL can now be optimized for use over a large surgical field without the need for a laser excitation source. When combined with a novel LED-based light source proposed in this study, and recent advances in cardiac and respiratory gating technology from the PI's laboratory, SMNL should be able to provide surgeons with direct measurement of [unreadable][unreadable]A, [unreadable][unreadable]S', and QY, and thus improve virtually all image-guided surgical interventions.